The present invention relates to a method and apparatus for mounting electronic components onto a circuit board, in particular, a method and apparatus for mounting electronic components with which time required for mounting is reduced when a plurality of electronic components are mounted onto a circuit board.
In recent years, in processes of mounting electronic components, improvement of reliability of work processes and reduction of work processing time are strongly required to improve productivity.
Conventionally, in an electronic component mounting apparatus for mounting electronic components such as chip components or IC chips onto a circuit board, by recognizing states that the electronic components are sucked and held by suction nozzles at a head by images picked up by using an image pickup device such as a CCD camera and collating the states with preset sucked and held states, movement of the head and the suction nozzles is controlled so as to mount electronic components at preset mounting positions on the circuit board, and thus electronic components are mounted on the circuit board.
A method of mounting electronic components onto a circuit board in such an electronic component mounting apparatus is explained below with reference to FIG. 17.
In FIG. 17, reference numeral 202 denotes an electronic component such as a chip component or an IC chip. Reference numeral 201 denotes a suction nozzle for sucking and holding the electronic component 202. This suction nozzle 201 can be moved up and down. Furthermore, this suction nozzle 201 is attached to a head 208, and the head 208 can be moved in an X-axis direction or a Y-axis direction shown in the figure by an XY table 205.
A plurality of electronic components 202 are housed in an electronic component feeding unit 203 and fed. By sucking and holding the electronic components 202 with suction nozzles 201, the electronic components 202 are taken out of the electronic component feeding unit 203. Then, by moving the head 208 by the XY table 205, the suction nozzles 201 are moved to above an image pickup device 204 located at a predetermined position while the electronic components 202 are being sucked and held, and when the electronic components 202 are positioned above the image pickup device 204, the XY table 205 is stopped.
Then, images of states that the electronic components 202 are sucked and held by the suction nozzles 201 are picked up by the image pickup device 204, these picked-up images are outputted to a control unit 206, and positions of the electronic components 202 relative to the suction nozzles 201 are recognized based on the aforementioned images in the control unit 206. Along with this, after image pick-up by the image pickup device 204, by moving the head 208 by the XY table 205, the suction nozzles 201 are moved to above a circuit board 207 fixed on an electronic component placement unit 209 while the electronic components 202 are being sucked and held. Then, relative positional corrections are performed based on results of relative positional recognition of the electronic components 202 relative to the suction nozzles 201 in the control unit 206, and thus the electronic components 202 are placed onto the circuit board 207.
However, in such a method for mounting electronic components, the electronic components 202 are mounted onto the circuit board 207 by repeating an operation where the suction nozzles 201 are moved from the electronic component feeding unit 203 to the image pickup device 204 and stopped above the image pickup device 204 by the XY table 205 for a time sufficient such that image pick-up of the components is performed by the image pickup device 204, an operation where, thereafter, the suction nozzles are moved towards the electronic component placement unit 209 and stopped above the electronic component placement unit 209, and an operation where, after the electronic components 202 are placed, the suction nozzles are moved again towards the electronic component feeding unit 203 and stopped above the electronic component feeding unit 203. Therefore, for example, time for operations that are not directly related to a mounting operation of the electronic components, such as a time for which the suction nozzles are stopped for image pick-up by the image pickup device 204, is extremely long, and there is an issue in that reduction of mounting time cannot be sufficiently addressed.
In order to solve such an issue, an electronic component mounting method has been proposed wherein static images of the electronic components 202 are picked up by providing the image pickup device 204 with an electronic shutter function, and using the electronic shutter function when the electronic components 202 pass above the image pickup device 204 by operation of the XY table 205 without stopping the suction nozzles 201.
Since deceleration time for stopping the suction nozzles 201 above the image pickup device 204 by operation of the XY table 205, time for image pickup by the image pickup device 204, and acceleration time for moving the suction nozzles to the electronic component mounting unit 209, can be reduced by such an electronic component mounting method, whereby reduction of mounting time can be addressed.
However, even in such an electronic component mounting method, an operation where the suction nozzles 201 are moved to above the image pickup device 204, which is an image pickup position, is required. Furthermore, due to a size of the mounting apparatus, a limitation in arrangement of component units on the mounting apparatus, and the like, it is difficult to dispose the image pickup device 204 on a line connecting the electronic component feeding unit 203 and the electronic component placement unit 209. Therefore, there is an issue that further reduction of mounting time cannot be realized.
In order to solve such an issue, there is an electronic component mounting method wherein an XY table includes both a head equipped with suction nozzles and an image pickup device, whereby the image pickup device is similarly moved with the suction nozzles while the suction nozzles on the head are being moved, and images of electronic components are picked up by the image pickup device during this movement of the suction nozzles and the image pickup device, so that time for moving the electronic components 202 to above image pickup device 204 is reduced. An example thereof is the electronic component mounting method described in Japanese Patent No. 2863731.
In order to further reduce the time for mounting electronic components by such an electronic component mounting method, the number of times the suction nozzles travel between the electronic component feeding unit and the electronic component placement unit needs to be reduced by increasing the number of suction nozzles of the head. Furthermore, time required for mounting electronic components also needs to be reduced by increasing a travel speed of the suction nozzles and shortening a travel distance of the suction nozzles.
However, when the number of suction nozzles of the head is increased, time required for picking up images of states that electronic components are sucked and held by the suction nozzles in the image pickup device, and time for recognizing these images, are increased in proportion to the number of suction nozzles. In addition, when a travel distance of the suction nozzles is reduced with an increase in the number of suction nozzles, a phenomenon occurs that travel time of the suction nozzles is shorter than time for which images are picked up, recognized and processed by the image pickup device. In such a case, since the electronic components cannot be placed onto the circuit board until pickup and recognition of images of the electronic components by the image pickup device are completed, there is an issue in that a loss occurs in time for mounting electronic components.
As practical electronic component mounting apparatuses, many apparatuses with about ten suction nozzles have been developed. When images of electronic components sucked and held by these suction nozzles are successively picked up, a time of 33 msec×10=330 msec is required as time required for image pickup when an image pickup device is a usual interlace type camera. Furthermore, even when a camera that outputs an image by a dual system is used as the image pickup device, a time of 16.5 msec×10 nozzles=165 msec is required as time required for image pickup. Furthermore, time of 100 msec is required for recognition processing of picked-up images. That is, at least a time of 265 msec is required to complete pickup and recognition of images of electronic components. On the other hand, a travel time of the suction nozzles is reduced to 200 msec. There is an issue in that reduction of the time for mounting electronic components cannot be expected even when the travel time of the suction nozzles is further reduced.
Accordingly, an object of the present invention is to provide an electronic component mounting method and apparatus by which time required for mounting electronic components is efficiently reduced, and hence productivity can be improved since, for a plurality of electronic components sucked and held by a plurality of sucking and holding members, images of states that the electronic components exhibit when sucked and held are picked up by an image pickup device and successively recognized, electronic components for which image recognition processing is completed are successively placed so that a placing operation of electronic components can be performed at the same time as work of image recognition processing even when recognition processing of images of the sucked and held states of all the electronic components is not completed, and thus solve the aforementioned issues.